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JEE Main 2023 · 29 Jan · Shift 1

JEE Main 2023 Physics question on Work Energy and Power

A stone is projected at angle 30° to the horizontal. The ratio of kinetic energy of the stone at point of projection to its kinetic energy at the highest point of flight will be -
  1. A.
    1 : 4
  2. B.
    4 : 1
  3. C.
    1 : 2
  4. D.
    4 : 3
Show answer and solution

Correct option: D

Solution

At the highest point, only the horizontal component of velocity remains: vx = v·cos30° = v·(√3/2).

KE_initial/KE_highest = (½mv²) / (½m·v²cos²30°) = 1/cos²30° = 1/(3/4) = 4/3.

So the ratio is 4 : 3.

[JEE Main 2023 · 29 Jan · Shift 1]

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